On the Origin of Interoception

Over the course of a century, the meaning of interoception has changed from the restrictive to the inclusive. In its inclusive sense, it bears relevance to every individual via its link to emotion, decision making, time-perception, health, pain, and various other areas of life. While the label for the perception of the body state changes over time, the need for an overarching concept remains. Many aspects can make any particular interoceptive sensation unique and distinct from any other interoceptive sensation. This can range from the sense of agency, to the physical cause of a sensation, the ontogenetic origin, the efferent innervation, and afferent pathways of the tissue involved amongst others. In its overarching meaning, interoception primarily is a product of the central nervous system, a construct based on an integration of various sources, not per se including afferent information. This paper proposes a definition of interoception as based on subjective experience, and pleas for the use of specific vocabulary in addressing the many aspects that contribute to it

Startle responding in the context of visceral pain

This study aimed to investigate affective modulation of eye blink startle by aversive visceral stimulation. Startle blink EMG responses were measured in 31 healthy participants receiving painful, intermittent balloon distentions in the distal esophagus during 4 blocks (positive, negative, neutral or no pictures), and compared with startles during 3 ‘safe’ blocks without esophageal stimulations (positive, negative or neutral emotional pictures). Women showed enhanced startle during blocks with distentions (as compared with ‘safe’ blocks), both when the balloon was in inflated and deflated states, suggesting that fear and/or expectations may have played a role. Men's startle did not differ between distention and non-distention blocks. In this particular study context affective picture viewing did not further impose any effect on startle eye blink responses. The current results may contribute to a better understanding of emotional reactions to aversive interoceptive stimulation

Unpleasantness and Fear in Interoception

_________________________________________Interoceptive fear (IF) is the apprehension of bodily sensations. IF is relevant to a number of psychiatric and somatoform disorders, in which fear learning to bodilysensations has been hypothesized to play an important role. Although IFconditioning (IFC) is of relevance to understanding the etiology of these disorders, thus far research has hardly addressed the basic fear response topography to experimentally induced interoceptive sensations.Human fear can be measured through self-report inquiring about subjective fear, unpleasantness, arousal, sense of control (dominance), and the extent to which an aversive event is expected (expectancy). A validated psychophysiological measure for the motivational intensity, i.e. for arousal, is skin conductance. Eye blink startle is modulated by motivational direction (pleasant vs unpleasant) and is used to measure it. Duringunpleasantness and fear, startle magnitudes are generally potentiated compared to emotionally neutral and pleasant states. The primary aim of this doctoral project was to find out whether the human eyeblink startle paradigm can be used to measure defensive response mobilization elicited by aversive interoceptive stimulation. To this purpose, a two-step approach was used: in a first step the concept of interoception was critically reviewed, while in a second step a series of empiricalstudies were conducted.The review on interoception traced the development of the concept to its modern day usage. This review proposes to consider interoception as the phenomenological perception of the state of the body, irrespective of how this perception is formed and whetherit is accurate or not. Labels are suggested for specific components of interoception that allow to classify sensations as similar or distinct.In the first study, participants adopted a flexed, an upright, and an extended posture. The reasoning was that postures can influence emotions, and thus perhaps impact startle. Also, differences in startle hadpreviously been observed in gastrointestinal (commonly associated with a flexed posture) vs respiratory (extended posture) stimulation. Study 1found startle magnitude to be higher during the extended posture, due to negative affectivity associated with that posture.In a second study, healthy participants were exposed to a cold pressor test (CPT), loaded breathing, and inhalation of CO2-enriched air. Startle amplitudes during interoceptive stimulation were decreased relative to when there was no stimulation. Respiratory stimuli showed a linearly decreasing slope during prolonged stimulation, while the CPT evoked a quadratic pattern.In the third study we observed a potentiated startle during painful esophageal stimulation in women, but not in men. In the fourth study, we used esophageal stimulation to establish a homoreflexive interoceptive conditioning paradigm in which a non-painful esophageal stimulus (conditioned stimulus, CS) preceded a painful esophageal stimulus (unconditioned stimulus, US) in a paired, but not in an unpaired group. Compared to the latter, participants from the paired group learned to fear the CS, as reflected in their US-expectancy ratings and skin conductance response. Women in the paired group also showed a trend towards increased startle in response to the CS (relative to a safe period). This response disappeared again during the extinction phase; on the other hand,in the extinction phase men in the paired group showed higher startle amplitudes during the CS.In summary, our findings indicate that during aversive interoceptive stimulation, there is quite some unexpected variability in startle responding that does not uniformly fit the usually observed pattern of exteroceptive fear potentiated startle. Known modulatory influences on startle that could explain the results are arousal and orientation of attention. Alternative explanations for the observed startle refer to the defense cascade model of Lang and colleagues,and the perceptual-defensive-recuperative model of Bolles and Fanselow._________________________________________Table of Contents CHAPTER 1 On the origin of interoception 1 1. Introduction 2 1.1 Scope of relevance 2 1.2. Communicating on interoception 4 2. History of a concept 6 2.1. Etymology 6 2.2 Semantic evolution 7 3. Aspects of interoception 11 3.1. Exogenous versus endogenous origins 11 3.2 Visceroceptor, visceroceptive, visceroception – a reference to efferent innervation 13 3.3 The homeostatic afferent pathways and early CNS processing of homeostasis 19 3.4 Interoception as integrated percept 21 4. Conclusions 25 CHAPTER 2 Interoceptive fear and its measurement 27 Interoceptive stimuli 28 Fear and unpleasantness 31 CHAPTER 3 Aims 35 3.1 Review: On the origin of interoception 35 3.2 Study 1: Effect of seated trunk posture 36 3.3 Study 2: Effects of cold pain and respiratory stimulation on startle in women 36 3.4 Study 3: Effect of visceral pain on startle 37 3.5 Study 4: Visceral fear learning 37 CHAPTER 4 Effect of Seated Trunk Posture on Eye Blink Startle and Subjective Experience: Comparing Flexion, Neutral Upright Posture, and Extension of Spine 41 1. Introduction 42 2. Materials and Methods 44 2.1. Participants 44 2.2. Ethics Statement 44 2.3. Sitting postures 44 2.4. Self-report measures 46 2.5. Somatic reflex measurement and processing 46 2.6. Procedure 47 2.7. Data analysis 48 3. Results 49 3.1. Manipulation check 49 3.2. Eye Blink Startle 49 3.3. Self-report 50 4. Discussion 51 CHAPTER 5 Atypical modulation of startle in women in face of aversive bodily sensations 55 1. Introduction 56 2. Materials and Methods 59 2.1. Participants 59 2.2. Stimuli and Apparatuses 59 2.3. Procedure 62 2.4. Data analysis 63 3. Results 65 3.1. Eye blink EMG 65 3.2. Self-report 66 4. Discussion 66 CHAPTER 6 Visceral pain modulates startle differently in men and women 71 1. Introduction 72 2. Methods 73 3. Data Analysis 76 3.1 Manipulation check 76 3.2 Eye blink startle. 76 3.3 Skin Conductance Levels 78 3.4 Evaluative judgments 79 4. Results 79 4.1 Manipulation check 79 4.2 Eye blink startle 80 4.3 Skin Conductance Levels 82 4.4 Evaluative judgments 82 5. Discussion 83 CHAPTER 7 Visceral fear learning as a mechanism of gastro-intestinal specific anxiety 87 1. Introduction 88 2. Methods 90 2.1. Participants 90 2.2. Stimuli 91 2.3. Measures 92 2.4. Procedure 93 3. Data reduction and analysis 96 4. Results 97 4.1. US-expectancy 97 4.2. SCRs 99 4.3. Startle eye blink EMG 100 5. Discussion 101 5.1. Pre-exposure and Acquisition 102 5.2. Extinction 103 5.3. Linear effects on startle 104 5.4. Gender differences 105 5.5. Limitations 107 CHAPTER 8 General Discussion and Conclusions 111 1 Overview of studies and their aims 112 2. Startle modulation 114 Study 1: Effect of seated trunk posture 114 Study 2: Cold pain and respiratory stimulation 115 Study 3: Visceral pain 115 Study 4: Visceral fear learning 115 3. Possible modulatory influences on startle 116 4. Skin Conductance 120 5. Fear and unpleasantness ratings 121 6. Limitations and future research 122 References 125 Appendix 147nrpages: 150status: publishe

Atypical modulation of startle in women in face of aversive bodily sensations

Eye blink startle magnitude is assumed to be higher in threatening contexts. A scarce amount of studies suggest that this does not hold true when startle is measured during perceived threats to homeostatic integrity. The present study was set up to describe the startle response pattern to a selection of interoceptive stimuli. Female subjects (N = 36) were exposed once to 90 s of continued (1) cold pain, (2) inhalation of a gas mixture of 7.5% CO2, and (3) breathing against an inspiratory and expiratory resistive load. Each stimulus was preceded and followed by a 90 second period of rest, respectively labeled baseline and recovery. Even after correcting eye blink startle responses for habituation, a decreased startle amplitude was evident during these stimuli. Results suggest that startle amplitude during aversive stimulation is inversely correlated with perceived fearfulness for women, although further studies are necessary to corroborate this interpretation

Accuracy and awareness of perception: Related, yet distinct (commentary on Herbert et al., 2012)

Herbert and colleagues (2012) state that changes in autonomic activity following a specific type of interoceptive sensation, intensifies general interoceptive awareness. This conclusion is being critically examined and reformulated. A distinction is made between Interoceptive Awareness (IAw) and Interoceptive Accuracy (IAc); awareness not necessarily implying accuracy. Given the heterogeneity of interoceptive sensations, we emphasize to abstain from concluding that heartbeat perception tasks can be considered as a measure of OVERALL IAw or OVERALL IAc until this has been more elaborately investigated. Results are reinterpreted to indicate that homeostatic challenges which lead to an increase in ionotropic cardiac activity, lead to an increased cardioceptive accuracy, and perhaps increased cardioceptive awareness. However, the findings do not provide conclusive evidence that such challenges increase other types of IAc, nor that they increase OVERALL IAw. Furthermore, it remains unclear whether homeostatic challenges leading to negative inotropic cardiac activity, would similarly lead to changes in accuracy of heartbeat perception

Detecting coached feigning using the test of Memory Malingering (TOMM) and the structured inventory of Malingered Symptomatology (SIMS)

Undergraduate students were administered the Test of Memory Malingering (TOMM) and the Structured Inventory of the Malingered Symptomatology (SIMS) and asked to respond honestly, or instructed to feign cognitive dysfunction due to head injury. Before both instruments were administered, symptom-coached feigners were provided with some information about brain injury, while feigners who received a mix of symptom-coaching and test-coaching were given the same information plus advice on how to defeat symptom validity tests. Results show that, although the accuracy of both instruments appears to be somewhat reduced by a mix of symptom coaching and test coaching, the TOMM and SIMS are relatively resistant to different kinds of coaching

Effect of seated trunk posture on eye blink startle and subjective experience: Comparing flexion, neutral upright posture, and extension of spine

Postures are known to be able to affect emotion and motivation. Much less is known about whether (affective) modulation of eye blink startle occurs following specific postures. The objective of the current study was to explore this. Participants in the present study were requested to assume three different sitting postures: with the spine flexed (slouched), neutral upright, and extended. Each posture was assumed for four minutes, and was followed by the administration of brief self-report questionnaires before proceeding to the next posture. The same series of postures and measures were repeated prior to ending the experiment. Results indicate that, relative to the other postures, the extended sitting posture was associated with an increased startle, was more unpleasant, arousing, had smaller levels of dominance, induced more discomfort, and was perceived as more difficult. The upright and flexed sitting postures differed in the level of self-reported positive affect, but not in eye blink startle amplitudes

Respiratory Gating of the Acoustic Startle Reflex: Preliminary Evidence

1 - Background According to Eckberg (2003) intraindividual, oscillatory changes in vagal and sympathetic outflow exist because of Respiratory Gating (RG). RG implies that the start of inspiration is associated with increased sympathetic activity, and the start of expiration with increased vagal outflow to the heart. Because interindividual differences in cardiac vagal motor output are predictive for the overall magnitude of the startle response, and for affective modulation of the startle reflex (Ruiz-Padial, Sollers, Vila, & Thayer, 2003), the aim of this study was to explore whether intraindividual changes in autonomic outflow (RG) affects the magnitude of the startle blink response. The research question was whether the magnitude of the startle is dependent on whether the acoustic startle probe is delivered during inspiration versus expiration? 2 - Method To answer our question we analyzed existing data of two interoceptive fear conditioning experiments (not specifically designed to answer this question). We partitioned startle responses in two: those of which the startle probe was presented during inspiration, and those of which the startle probe was presented during expiration. We then compared for each of the different phases in the experiments, whether there were differences between startles to probes delivered during inspiration versus those delivered during expiration. 3 - Results & Discussion Startle was greater when probes were delivered during expiration compared to inspiration, but this was only so during times when no respiratory loads were applied (the extinction phase of the conditioning experiment). The results are not widespread enough to have implications for adjusting the timing of the administration of startle probes: we assume that if there are any effects on startle magnitude, these effects will level out due to the variable and random presentation timing of the probes. Moreover, the respiratory cycle is not the most fine-graded measure of vagal and sympathetic outflow, which warrants caution in interpreting these results.You may refer to the abstract and accompanying poster as follows: Ceunen, E., Pappens, M., Van den Bergh, O., & Van Diest, I. (2009). Respiratory Gating of the Acoustic Startle Reflex: Preliminary Evidence. Annual Meeting & Symposium on Respiratory Psychophysiology. Berlin, 25-27 October 2009.status: publishe

Eye-Blink Startle Response is Potentiated by Cold Pressor Pain But Inhibited by CO2-Induced Breathlessness

Background Eye-blink EMG startle potentiation is observed in negative situations and negative emotional states, as well as in defensive responding to threat. The existing evidence supporting EMG startle potentiation as a defensive response is mainly based on exteroceptive stimuli – e.g., pictures or electrical stimuli. Evidence concerning EMG startle modulation in response to physical threat is scarce, however, although EMG startle potentiation has been observed in response to heat pain. Methods We investigated EMG startle modulation in response to cold pressor pain (n=16; 1 minute 2°C immersion of non-dominant hand) and CO2-induced breathlessness (n=13; 1 minute 10% CO2-enriched air inhalation). Six auditory startle probes were presented: two probes during the minute preceding the challenge (baseline), two probes during the challenge and two further probes during the minute following the challenge (recovery). The first probe of each phase was presented in the first 30 seconds, the second probe in the last 30 seconds. Results & Discussion No differences in EMG startle responding were observed during baseline or recovery. The challenge resulted in EMG startle potentiation in reaction to cold pressor pain and EMG startle inhibition in response to CO2-induced breathlessness. The latter may be due to breathlessness – in contrast to pictures, electrical stimulation or pain – being an interoceptive stimulus, directing attention inwards and reducing attention to external threats. Alternatively, CO2-induced breathlessness may be experienced as a circa-strike situation in which EMG startle modulation is generally reduced.The poster abstract has been published in a supplement to the 46th volume of the Journal 'Psychophysiology' on page s75, and may be referred to as: De Peuter, S., Ceunen, E., Van Diest, I., Van den Bergh, O., Vlaeyen, J. (2009). Eye-Blink Startle Response is Potentiated by Cold Pressor Pain But Inhibited by CO2-Induced Breathlessness. Psychophysiology: vol. 46 (Supplements s1). Forty-Ninth Annual Meeting of the Society for Psychophysiological Research. Berliner Congress Center, Berlin, Germany, 21–24 October 2009, s75. (For access to a digital copy of the poster, see bottom of this page)status: publishe